This invention relates generally to drive systems. More particularly, it relates to an assembly which is adapted to drive the accessories in a vehicle. In such an adaptation, a compact gear differential is used to boost accessory speeds at relatively low engine speeds, thus allowing lower accessory speeds at relatively high engine speeds.
Modern vehicle engines are called upon to drive an increasing number of accessories. As much as twenty-five percent of the engine brake horsepower available may be required to drive them. Thus the efficiency of the accessory drive system is important in so far as it relates to fuel economy.
The ideal condition would be to drive the accessories at a constant speed. This is impractical in an automotive vehicle. Generally an accessory drive system drives accessories at some speed which is a linear function of engine speed. At low engine speeds, for example at engine idle speed, the accessories may be driven so slowly as to be inefficient. Similarly, at high engine speeds the accessories may be driven too fast for efficient operation. There remains a need in the art for a simple, inexpensive accessory drive assembly with the capability of compressing the accessory drive speed range as compared with the engine speed range of an associated vehicle.